The trucking industry has for many years used tractor/trailer combinations to transport cargo over the roadways to intended destinations. The tractors and the trailers are mechanically coupled together so that the tractor can pull the trailer with its cargo in an efficient and cost effective manner.
Various links between the tractor and the trailer provide vehicle subsystems with power and/or control signals to operate. Thus, hydraulic, pneumatic, electrical and other subsystems on the tractor/trailer combination have associated electrical conductors and pneumatic lines running therebetween so these subsystems can operate.
With regard to electrical subsystems, both the tractor and trailer operate in a manner which requires coordination between the electrical components on each to operate the tractor/trailer combination safely and effectively. In order to coordinate such operation and further to supply power from the tractor to the trailer, a seven-pin connector has been used by the trucking industry to accomplish these and other electrical objectives. The connector includes two disengageable connector portions to permit the tractor and trailer combination to be disconnected. An example of such a seven-pin connector is illustrated in U.S. Pat. No. 4,969,839 to Nilsson, the entire disclosure of which is specifically incorporated herein by reference. These seven-pin connectors are well known and have been specified by the Society of Automotive Engineering (SAE) according to the standard number "SAE J560" the teachings of which are also incorporated herein by reference. Thus, one need only ask for an SAE J560 connector from an appropriate manufacturer and the standard seven-pin connector will be delivered.
Each of the pins in the standard seven-pin connector is an electrical conductor carried by the plug portion of the connector and which is adapted to mate with a corresponding electrical contact in the receptacle portion of the connector to thereby bus an electrical signal between the tractor and the trailer. The signals generally relate to specific electrical subsystems, for example, ground, turn signals, brake lights, clearance lamps, flashers, and other devices which require electrical power to function. The seventh pin on the connector is usually an "auxiliary" pin which can be used for specific electrical purposes or applications on individual tractor/trailer combinations.
The trucking industry has not until very recently incorporated sophisticated electrical and electronic subsystems in tractor/trailer combinations which perform varied tasks that usually involve data manipulation and transmission. Computers, controllers, and computer-type electrical systems have simply not found their way into the tractor/trailer combination in any significant fashion up to now due, in part, to the low level of technological innovation in the trucking industry and further due to a lack of governmental or other authoritative impetus which would otherwise require systems to be installed on tractor/trailers that include sophisticated electronics and data communications.
However, with the advent of new anti-lock braking subsystems (ABS) for example, and other new subsystems which promote tractor/trailer safety and enhanced performance, microprocessors have found their way into use in the trucking industry, and specifically in applications involving tractor/trailer combinations to enhance the performance of these new subsystems. It is apparent that the use of computers and microprocessors in general in the trucking industry will continue to expand and provide ever increasing capabilities to tractor/trailer combinations in a wide range of applications.
Along with the sophistication of computer and electronic subsystems comes the requirement of equally sophisticated and versatile data communications between microprocessors and devices which use data output from the computers, or which input data to the computers. Thus, it is desirable to develop and implement data communication links and circuits to provide the microprocessors and systems in tractor/trailer combinations with reliable data communication. This is particularly true when data must be communicated between data producing devices and data receiving devices that may be found both on the tractor and the trailer, and when data must be transmitted between the tractor and the trailer. An example of this type of data communication between the tractor and the trailer is found in an ABS subsystem where data about the performance of the brakes on the trailer is desirably communicated to a computer in the tractor which will, in turn, further actuate control valves on the trailer to control the ABS's performance.
Unfortunately, the standard seven-pin connector, ubiquitous in the trucking industry, is simply not suited to provide sophisticated data communications between the tractor and the trailer. The seven-pin connector has only been used in the past to provide analog electrical signals, particularly power, to low-level, unsophisticated electrical subsystems in the tractor/trailer combination. Yet, the J560 seven-pin connector is an industry standard which is used in virtually every tractor/trailer in service today and so is likely to remain in service for many years. In addition, the same J560 connector is used and thus similarly hampers agricultural applications in the operation of implements towed by farm tractors. Also, the International Standards Organization (ISO) sets standards for international markets, such as in Europe and Japan, and one of their connector standards is nearly identical to those of the SAE J560.